LTPS thin-film transistor (TFT) liquid crystal display (LCD) has better performance than conventional amorphous silicon TFT LCD. For example, the LTPS TFT LCD can have an electron mobility greater than 200 cm2/V-sec, which can help reducing a size of a TFT component, and further increasing its aperture ratio, i.e., increase the brightness of the TFT LCD. And the power consumption of the TFT LCD may be reduced. Besides, under the relatively high electron mobility, a portion of driving circuits can be integrated on a glass substrate, such that the number of integrated driving circuits may be reduced and the reliability of a LCD panel may be greatly enhanced, which may greatly reduce manufacturing cost of the LCD panel. Therefore, the LTPS TFT LCD has become a research focus gradually. Generally, an LTPS TFT LCD includes an array substrate and a color film substrate opposite to the array substrate.
In existing techniques, a metal layer of a storage capacitor or a pixel electrode may be enlarged to increase pixel capacitance, however, this may reduce an aperture ratio of pixels. Besides, in an existing pixel structure, the pixel capacitance consisting of a trench layer, a gate insulating layer and a first metal layer generally accounts for about 10% of the whole pixel capacitance, thus, increment of the area of the metal layer may not lead to obvious increment of the whole pixel capacitance.